doc: Use newer coding conventions in examples/code directory. * FIRfilter.m, FIRfilter_aggregation.m, display.m, subsasgn.m, subsref.m, display.m, end.m, get.m, numel.m, plot.m, polynomial.m, polynomial_superiorto.m, polyval.m, roots.m, set.m, subsasgn.m, subsref.m, celldemo.cc, fortrandemo.cc, funcdemo.cc, globaldemo.cc, oct_demo.cc, paramdemo.cc, stringdemo.cc: Use newer coding conventions in examples/code directory.